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Effects of Top-quark Compositeness on Higgs Boson Production at the LHC

Motivated by the possibility that the right-handed top-quark (t_R) is composite, we discuss the effects of dimension-six operators on the Higgs boson production at the LHC. When t_R is the only composite particle among the Standard Model (SM) particles, the (V+A)\otimes (V+A) type four-top-quark contact interaction is expected to have the largest coefficient among the dimension-six operators, according to the Naive Dimensional Analysis (NDA). We find that, to lowest order in QCD and other SM interactions, the cross section of the SM Higgs boson production via gluon fusion does not receive corrections from one insertion of the new contact interaction vertex. We also discuss the effects of other dimension-six operators whose coefficients are expected to be the second and the third largest from NDA. We find that the operator which consists of two t_R's and two SM Higgs boson doublets can recognizably change the Higgs boson production cross section from the SM prediction if the cut-off scale is \sim 1TeV.